Gas fuel mixer for internalcombustion engines



25,, 1950 H. F. SHEPHERD ETAL, 2,505,725

GAS FUEL MIXER FOR INTERNAL-COMBUSTION ENGINES Filed D90. 23, 1946 2 Sheets-Sheet l FIG.|

INVENTOR-S H41 0 ishepherd Car/ W.Hr'eson 15y ATTORNEY A ril 25,, 1950 H. F. SHEPHERD ETAL 2,505,725

GAS FUEL MIXER FOR INTERNAL-COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed Dec. 25, 1946 F 2 INVENTORS Ham/ 1 fish /7M1 and ar/ \A/- firesoO ATTORNEY Patented Apr. 25, 1950 GAS FUEL Mrxsa ron INTERNAL- COMBUSTION ENGINES Harold F. Shepherd and Carl W.

field, Ohi

Pennsylvania 0, assignors to The National Company, Pittsburgh, Pa.,

Areson, Springpply a corporation of Application December 23, 1046, Serial No. 117.910

This invention relates broadly to supplying gaseous fuel to a Diesel engine for the purpose of operating the Diesel engine as a dual fuel engine, thereby increasingits range of usefulness and operation.

Any Diesel engine is readily adaptable to the use of a gaseous fuel. The simplest form of conversion is accomplished by fitting a mixer, consisting of a venturi with a central air manifold inlet.

As described in the abandoned application for improvements in Governor control mechanism for dual fuel engines, filed by Albert B. Reese, Jr., on'February 2, 1946, bearing Serial No. 645,143,

gas jet, to the and assigned to The National Supply Company,

ordinary mechanical governors which are inherently damped or slow of acceleration due to the use of relatively large centrifugal masses opcrating in small orbits with resulting small actuating force. When supersensitive governors, particularly isochronous governors usually of the hydraulic type, are employed serious surging may be set up if the gas is introduced directly into the manifold.

Two influences operate to produce the results noted above, particularly with multiple cylinder engines.

First.--At any crank center an eight cylinder engine, for example, has one cylinder beginning its power stroke, one cylinder on compression, one cylinder beginningcompression and one cylinder at half suction stroke. Thus, three and one-half charges are already beyond the influence of the governor, plus the number of charges contained in the inlet manifold.

Second.--The Otto cycle gas engine using spark ignition is charged, at all loads, with gas and air in the approximate proportions of the perfect or explosive mixture. In the true sense it has no overload capacity since it cannot produce any appreciable excess of power by increasing the fuel quantity. It cannot be effectively controlled by reduction of the gas quantity alone, since a non-firing mixture results at approximately half load and regulation becomes hit or This simple system is in use onengines using 2 Claims. (Cl. 123-120) miss. The Diesel engine in which combustion is initiated by spontaneous ignition of jets of Diesel oil into the gas and air charge burns extremely attenuated mixtures. Furthermore, since the full load mixture itself is very lean, to conform to the normalDiesel rating, it is capable of large overloads.

For these two reasons it is possible for a very active governor on a gas-Diesel or dual fuel englue to over-respond to speed changes and over regulate, then to surge uncontrollably in its attempt to suit the fuel to the load. To assist in overcoming the above objectionable feature it has been common practice to feed gas to each individual cylinder intake through nozzles discharging closeto the intake valves. This is only a partial solution since with few cylinders all the nozzles discharge some gas continuously if under slight pressure. If under slight vacuum the nozzle at the cylinder which is aspirating draws not only gas from the fuel source but also gas and air from all the other nozzles with resulting uncertain distribution.

It is, therefore, the principal object of this invention to provide means to definitely and individually control the amount of gas entering each cylinder at the proper time for eflicient operation.

Another object of this invention is to provide a means to govern and distribute the gas admitted to each cylinder in a dual fuel engine such that the gaseous mixture from the adjoining inlet passages does not enter the cylinder to which the gas charge is being delivered.

Another object of this invention is to provide each cylinder inlet gas nozzle with a lightly loaded check valve at or near the end of each nozzle.

Another object of this invention is to provide means to prevent an uncontrolled supply of gaseousfuel from contaminating the air in the air manifold leading to the mixing chambers provided for each cylinder.

Further objects and advantages of this invention will be obvious and in part specifically referred to in the description and specification to follow, which taken in conjunction with the accompanying drawings, discloses a preferred form of an apparatus in accordance with this invention. It should be understood; however, that the disclosure is only illustrative of the principles of our invention in its broader aspects.

Figure 1 is a schematic fragmentary view, partly in cross section, taken through the intake manifold showing its relation to the engine cylin ders and partly diagrammatic to indicate the in- 3 dividual fuel nozzles. each provided with a lightly loaded check valve, and arranged to inJect fuel directly into a separate mixing chamber for each cylinder, to illustrate the operating features of our invention.

Figure 2 is an enlarged cross sectional view taken along the line 2-2 of Fig. 1', showing the detailed construction of one of the spring loaded check valves referred to in Fig. 1. The fuel pipe leading to the ignition nozzle is not shown in section for the purpose of simplicity.

In carrying out our invention the conventional valve and head design of a multi-cylinder Diesel engine is used. The preferred form of our invention, disclosed in Figures 1 and 2, shows only the operating mechanism required for the proper admission of a separate charge of gaseous fuel to an individual mixing chamber receiving its air from a common header or air inlet manifold.

In the drawings the numeral i designates a fuel oil pump designed to supply 011 fuel to the engine cylinders 2 through the oil fuel lines 3 in a conventional manner not shown. The amount of oil fuel delivered to the cylinders 2 is controlled by the governor 4 operatively connected to regulate the speed of the engine at the imposed load.

Air in the proper amount for Diesel operation is delivered to each engine cylinder 2 through individual inlet passages 5 connected to a main header or air inlet manifold 5, receiving its air from the atmosphere through the intake 1.

In changing over from oil to a gaseous fuel the governor 4 automatically reduces the amount of 011 fuel to the quantity. allowed by the fuel pump stop, described in the Reese co-pending application referred to above, to a predetermined amount for maintaining ignition and then progresses into the gas control range acting on a butterfly or other simple valve 8 to regulate the quantity of fuel gas required to maintain engine speed at the imposed load.

Fuel gas under slightly sub-atmospheric pressure or at a slight pressure, maintained by a regulator (not shown)- is admitted through valve 5 into the line ill, from whence it flows to a gas manifold Ii, from which branch lines l2 lead to the interior of the individual air inlet passages 5, passing through apertures It in the inlet manifold 6. The branch lines I! extend to a predetermined position within the inlet passages 5 and terminate in a nozzle ll upon the end of which is mounted an outwardly opening,

lightly loaded sprin actuated check valve l5 of the flutter or harmonic type.

The use of this check valve i5 prevents an uncontrolled supply of gaseous fuel from contaminating the air in the air manifold 6 leading into the mixing chambers 5. As pointed out earlier in our specification one of the principal objections to receiving a mixture of air and gas from a common header or inlet manifold comprising a mixing chamber is that of over-charging the cylinder due to the correlated action of the other cylinders in the engine block. It can be shown that without the use of our check valve three and one-half charges in an eight cylinder engine are already beyond the influence of the governor, plus the number of charges contained in the inlet manifold. Hence the only proper and efficient manner to utilize gas as a fuel in a dual fuel engine is to definitely govern and regulate the distribution of this fuel to each cylinder.

, that many changes may be made therein witha Number out departing from the spirit of the invention in its broader aspects and we do not wish to be limited or restricted to the specific details set forth but wish to reserve to ourselves any further embodiments, modifications and variations that may appear to those skilled in the art or fall within the scope of the .appended claims.

Having fully disclosed our invention, what we claim as new and desire to secure by United States Letters Patent is:

1. In apparatus for controll ng gaseous fuel to a multi-cylinder internal combustion engine in which air required to maintain proper combustion in the cylinders is supplied through a common air inlet manifold having relatively restricted individual air inlet passages branching from said manifold and leading to each cylinder, said passages serving as independent combustible mixing chambers for each cylinder, a common gas inlet -manifold, individual gas inlet lines branching from said gas manifold, each said line extending-individually to a predetermined position within each of said mixing chambers. a gaseous fuel injection nozzle positioned on the outer end of each gaseous inlet branch line and within said mixing chambers and a check valve positioned on the outer end of each nozzle and actuated solely by the aspiration of each individual cylinder during its fuel charging period.

2. Apparatus for delivering a regulated quantity of gaseous fuel to a muti-cylinder engine provided with a common air inlet manifold and a common gaseous fuel inlet manifold, comprising relatively restricted individual air inlet passages branchingfrom said common ar inlet manifold and leading directly to each cylinder, individual gas inlet lines branching from said common fuel inlet manifold and extending to a predetermined position within each restricted air passage, a gaseous fuel injection nozzle positioned on the outer end of each gas inlet line and a check valve positioned on the outer end of each nozzle and actuated solely by the aspiration of each respective cylinder during its fuel charging period.

HAROLD F. SHEPHERD. CARL W. ARESON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Lee Mar. 6, 1928 Schmdt Sept. 2, 1930 Chandler Sept. 8, 1931 Schweizer Feb. 25, 1941 Boyer May 1, 1945 Miller et al May 14, 1946 Winfield Nov. 15, 1938 

